Vuex異步請求存取步驟

 --------------------------
 vuex 
 1.首先在state中創建變量
 export default {
   // 首頁輪播圖
   homecasual: []
 }
 2.然后在action中調用封裝好的axios請求，異步接收數據，commit提交給mutation
 引入
 import {
   getHomeCasual,
 } from '../api'
 ------------------
 引入mutationtype規范---
 import {
   HOME_CASUAL,
 } from './mutation-types'
 介紹一下這里---
 在mutation-types中創建
 export const HOME_CASUAL = 'home_casual'; // 首頁輪播圖
 -----------------------------
export default {
  // 1. 獲取首頁的輪播圖
  async reqHomeCasual({commit}, callback) {
    const result = await getHomeCasual();
    commit(HOME_CASUAL, {homecasual: result.message.data})
    callback && callback();
   },
  }
  ---------------
  3.在mutations中改變state中的狀態
  引入規范
  import {
     HOME_CASUAL,
  } from './mutation-types'
  將從actons中獲取到的值賦值給state
export default {
  [HOME_CASUAL](state, {homecasual}){
      state.homecasual = homecasual;
  },
 }